Results ofmvestigations on pulse lengthening of a TE-C02-laser for materials processing will be reported. The laser is used in two main modifications both working at an absolute pressure of lower than 300 mbar. With a folded resonator pulse durations up to 20 sec have been achieved. As there is no longer the initial peak but a descending saw-tooth like form, one can get mean powers up to 100 kW and maximum powers up to 300 kW. Using a so-called hybrid-resonator containing a cwCO2-laser-section,there are even better pulse shapes within about 10-15 jisec, but containing lower pulse energies up to /2 Joule. The influence ofparameters e.g. absolute pressure of working gas or gas mixture on pulse form and duration and results of cutting and drilling of metals like Al or Cu will be presented.